Question

Calculate the concentration of an aqueous Ba(OH)₂ solution that has pH = 10.50.

Short answer

The concentration of a Ba(OH)₂ solution that has pH = 10.50 is 1.6×10^-4 M.

Step-by-step solution

OH- Concentration Calculation of Ba(OH)2 Solution

Ba(OH)₂ is a strong base so dissociates completely.

At 25°C,

$$\begin{gathered} \mathrm{pH}+\mathrm{pOH}=14 \\ \mathrm{pOH}=14-\mathrm{pH}=14-10.50=3.50 \\ \mathrm{pOH}=-\log \left[{\mathrm{OH}}^{-}\right] \\ \left[{\mathrm{OH}}^{-}\right]={10}^{-\mathrm{pH}}={10}^{-3.5}=3.2\times {10}^{-4} \end{gathered}$$

Calculation of Concentration of Ba(OH)2 Solution

As, Ba(OH)₂ is a strong base, and 1 mol of Ba(OH)₂ gives 2 moles of OH^- ions so,

$\mathrm{Conc}.\mathrm{of}\mathrm{Ba}{\left(\mathrm{OH}\right)}_2=\frac{\mathrm{Conc}.\mathrm{of}\left[{\mathrm{OH}}^{-}\right]}{2}=\frac{3.2\times {10}^{-4}}{2}=1.6\times {10}^{-4}$